1. Technical Field of the Invention
The present invention relates to a method of carrying out aggregate exposed finish for architectural decorative concrete, and particularly to a method of carrying out aggregate exposed finish for concrete capable of extremely reducing the usage amount of expensive decorative aggregates, and of facilitating the work without requiring the long working time and the technique of a high skill level.
2. Description of the Prior Art
For carrying out aggregate exposed finish for decorative concrete, there has been mainly used a technique called a washing method until now. As for this washing method, there has been adopted such a method that mortar mixed with aggregates is placed on the substrate of concrete; and the mortar on the surface is washed away in the state that the mortar is still plastic to expose part of the aggregates. In recent years, there is a tendency of using such a technique that mortar mixed with aggregates is placed on the substrate of concrete; and then a surface retarder is sprinkled on the surface of the mortar. Further, the special sheet called a retarder paper tends to be used. In these methods, the hardening of the mortar on the surface is retarded, and when only the interior of the mortar is hardened, the unhardened surface layer is washed away, to expose part of the aggregates.
However, the prior art washing method described above has the following disadvantages: namely, a large amount of inorganics containing heavy metal and the like must be treated because mortar is washed away with a large amount of water; expensive decorative aggregates in an amount more than necessary must be used; and a long working time and the technique of a high skill level must be required for carrying out the decorative finish with a complicated pattern. Thus, there has been strong demands to solve the above disadvantages.